Round-cornering machine



May 19, 1959 .1. o.w|-u"rc:'c 1vn5 ROUND-CORNERING MACHINE 5 Sheets-Sheet 1 Filed Dec. 13, 1956 INVENTOR JOHN o. WHITCOMB ATTORNEY y 1959 I J. o. WHITCOMB 2,887,156

ROUND CORNERING MACHINE Filed Dec. 15. 1956 5 Sheets-Shet 2 INVENTOR JOHN O. WHITCOMB ATTORNEY 5 Sheets-Sheet 5 Filed Dec 1;, 1956 May 19, 1959 J. o. wHiTc MB ROUND-CORNERING MACHINE 5 Sheets-Sheet 4 Filed Dec. is, 1956 '3 JOHN O. WHITCOMB 7 ATTORNEY I May '19, 1959 J. o. WHITCOMB ROUND-CORNERING MACHINE 5 Sheets-Sheet 5 Filed Dec. 15, 19 56 INVENTOR JOHN o. WHITCOMB ATTORNEY United States Patent ROUND-CORNERING MACHINE John O. Whitcomb, Mechauicsburg, Pa., assignor to W. 0. Hickok Manufacturing Company, Harrisburg, Pa., a corporation of Pennsylvania This invention relates to a cornering machine, and more particularly to a machine for rounding the corners of packs of paper sheets for use in loose-leaf binders, etc. This invention is an improvement over the structure shown in the patent to Charles C. Cruzan, No. 2,656,888, granted October 27, 1953.

In the prior patent referred to there is disclosed a fully operative mechanism for rounding the corners of packs of paper sheets provided opposite edges of the packs are perpendicular to the supporting surface on which the cutting operation is being performed, the knives which cut the corners of the pack being movable vertically and exactly parallel to each other. In the cutting of packs of paper sheets with conventional guillotine cutters, however, opposite edges of a pack of sheets frequently, and in fact usually, are not exactly parallel to each other and perpendicular to the planes of the top and bottom of the pack, due to what is known in the art as drawing."

Where the side edges of a pack of sheets are not accurately cut, it will be apparent that when the stack of sheets is placed in the round-cornering machine, the sheets at one side of the pack will have their edges lined up vertically by the guide means forming a part of the apparatus. The edge of the pack at the opposite side thereof will not be vertical and may slightly incline downwardly and outwardly from the pack or downwardly and inwardly. Therefore, when the associated corner cutting knife is moved vertically downward to perform the cutting operation, an inaccurate cutting operation will result.

Assuming that the edge of the pack referred to slopes downwardly and inwardly relative to the pack, the top sheet will be accurately cut and progressive inaccuracy will occur throughout the remainder of the height of the pack, the lowermost sheets having fairly abrupt corners left thereon since the extremity of the cutter at the side of the pack will be spaced from the latter. Where the pack has one edge sloping downwardly and outwardly from the pack, it will be apparent that if the associated cornering knife is arranged accurately with respect to the top sheet of the pack, the extremity of the blade at the side of the pack will cut inside of the sheet edge to an increasing extent in which case the motor will stall and the knife will be arrested part way through the pack. The apparatus of the patent referred to, therefore, while advantageous and fully operative, does not take care of the situation involved when the packs of sheets are inaccurately cut, as is usually the case.

An important object of the present invention is to provide a round-cornering machine which performs an accurate round-cornering operation on the pack regardless of the parallelism of opposite sides of the pack.

A further object is to provide such an apparatus having novel means for supporting at least one of the corner cutting blades for operation so as to accurately cut the associated corner of the sheet regardless of whether the side of the pack of sheets is vertical or inclined from the vertical.

A further object-is to providesuch an apparatus having means associated with one of the corner cutting blades and engageable with the side of a pack of sheets which might be out of parallelism with the opposite side of the pack to automatically tilt the guide means for the cutting blade in either direction from the vertical in accordance with the inaccurate cutting of the pack.

A further object is to provide an apparatus of this character wherein one of the cornering blades is mounted for direct vertical movement in suitable guide means fixed against tilting movement and wherein the blade for cutting the opposite corner of the pack is mounted in guide means adapted to rock as may-be necessary so that the path of movement of the cutting blade will be parallel to the plane of an inaccurately cut side of the pack in order that the resultant corners will be accurately rounded.

A further object is to provide novel means for supporting the tiltable guide for one of the corner cutting blades and to bias such guide means away from a truly vertical position which it may occupy or from which it may be moved to accommodate the guide means for the associated blade to the plane of the inaccurately cut side of the pack.

A further object is to provide an apparatus of the character just referred to wherein the tiltable guide is mounted for lateral movement and normally positioned away from the edge of the pack and to provide means for automatically releasing the guide for movement into engagement with the adjacent edge of the pack, which engagement automatically tilts the guide, if necessary, to

properly position the associated blade to accurately cut' the adjacent corner of a pack.

A further object is to provide novel, substantially frictionless means for supporting the guide for one of the corner cutting blades to facilitate its quick and accurate tilting to accommodate the associated blade to the inaccurately cut side of the pack to be cornered.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the drawings I have shown one embodiment of the invention. In this showing:

Figure 1 is a front elevation of the apparatus, a portion being broken away;

Figure 2 is a horizontal section on line 2--2 of Figure 1; I

Figure 3 is an enlarged fragmentary front elevation of the apparatus, parts being shown in section, the parts being shown in their normal biased positions and with the cutting blades retracted;

Figure 4 is a similar view showing a portion of the apparatus illustrated in Figure 3 with the parts tilted to different positions and with the cutting blade shown moved downwardly from its normal inoperative position- Figure 5 is a section taken substantially on line 5-5- of Figure 4;

Figure 6 is a detail sectional view of the lateral retracting means for one of the cutting devices shown in normal inoperative position;

Figure 7 is a detail exploded perspective view of a rocker plate for supporting one of the guides for one of i the cutting blades, parts associated with the blade being illustrated;

Figure 8 is an edge elevation of a pack of sheets showing an inaccurately out side thereof sloping downwardly and outwardly relative to the pack; and

Figure 9 is a similar. view showing a cut edge of the pack sloping downwardly and inwardly relative thereto.

Referring particularly to Figures 1 and 3, the numeral 16) designates a supporting frame as a whole having an upper horizontal bed frame 11. supporting the cutting mechanism for the apparatus as vdescribed below. The particular structure of the supporting frame is of no Patented May 19, 1959 importance in connection with the present invention. The source of power for driving the present apparatus comprises an electric motor 12 supported bythe frame and carrying a pinion 13 meshing with a gear 14 mounted on a normally freely rotatable element 15 of a clutch 16 supported on a cross shaft 17} The clutch 16 comprises a member 18 fixed with respect to the shaft 17. The clutch 1 6 is a conventional single revolution clutch which need not be specifically described and is rendered operable upon energization of a solenoid 19 to actuate a lever 20. The clutch 16 is normally inoperative and accordingly the motor 1 2 is constantly rotated without imparting rotations to the shaft 17.

A treadle 22 forwardly of the frame 10. is depressible by the operator to close a switch 23 to energize the solenoid 19, whereupon the clutch 16 becomes operative for effecting one complete rotation of the shaft 17. This shaft has associated therewith an automatic brake 24 which comes into operation upon completion of a single rotation of the shaft 17 to promptly arrest such rotation. The shaft 17 is mounted in bearings 26 carried by the frame 10, and outwardly of each of these bearings a disk 27 is fixed to the shaft, each disk carrying a crank 28 connected to the lower end of a connecting rod 29.

The upper ends of the connecting rods 29 are connected as at 32 to a heavy transverse cross head 33 having bearings 34 slidable on vertical rods 35. The lower ends of these rods are fixed in collars 36 carried by heavy rigid arched supports 37 having at opposite ends base portions 38 seating on and overlying a pair of parallel spaced plates 39 resting on the bed plate 11. The base portions 38, plates. 39 and bed plate 11 are rigidly fixed to each otherin any suitable manner.

Referring to Figures 2 and 5, it will be noted that the bed plate 11 is provided with an elongated opening 42 the edges of which are spaced a shorter distance apart than the inner edges of the plates 39, thus forming hori-. zontal shoulders 43. A relatively heavy horizontal plate 44 rests on the shoulders. 43.. The plate 44: isfixed in adjusted positions longitudinally of. the shoulder-1'43 in any suitable manner. for example as described below. The plate 44 is provided therethrough with an opening 45, for a purpose to be described. Fixed to the top face of the plate 44 is'a supportingbase 46 carrying a vertically extending guide 47 having angularly inturned flanges 48 to each of which is fixed a wear plate 49 forming a slide bearing. Referring to Figures 1 and 3, it will be noted that the slide bearing 49 extends substantially abovev and below the plates 11 and 39 to provide a long bearing surface for a purpose which will become apparent.

A cross head 52 has. angular surfaces. sliding against the Wear plates 49 and has rear. spacedifaces 53 slidable against the inner face of-the guide 4 7. The cross. head 52' is provided with opposite flanges 56 between which ismounted a cutter bar 57 having a sharpened lower. edge 58. The cutter bar- 57 is formed with its inwardly and forwardly facing surface formed in cross section as shown in Figure 2 to cut the adjacent corner of a pack of sheets indicated by the numeral 59.

One corner of the plate 44 adjacent the opening 45 therein is provided with a recess 60 carrying a die block 61 adjustably fixed to the plate 44 as at 62. Obviously the block 61 is stationary and when the cutter bar 57 is moved downwardly from its normal position, the adjacent corner of the pack 59 will be rounded.

The elements comprising the cross head 52 and its guide 47, block 61, etc. constitute one. round-cornering unit indicated as a whole by the numeral 65. This unit has its elements always perfectly vertical and fixed against movement. exceptwhen it is desired to adjust it along the shoulders 43 for packs of different widths. Av generally similar cornering unit 66fis provided for cutting the opposite corner of the pack inserted into the machine. All of the parts of the unit which are identical with those of the unit 65 have been indicated by the same reference numerals.

The round-cornering unit 66 is provided with a plate 70 arranged in the opening between the rails 39 and corresponding generally to the plate 44. Whereas the plate 44 has its bottom edge seating on the shoulders 43, the plate 70 is undercut as at 71 (Figure 7) at opposite sides thereof to form surfaces spaced above the shoulders 43. Guide plates 72 (Figure 5) are provided with portions underlying the bed plate 11 at each side of the opening 42 and are secured at opposite sides of such opening to the plate 70 by a plurality of screws 73. The undercuts 71 of the plate 70 slope upwardly and inwardly from the longitudinal extremities of the plate 7t) as indicated by the numeral 74 (Figures 3 and 7), and at the center of the plate 70, a semi-cylindrical notch 75 is formed in each of the undercuts 71. A bearing plate '73 is arranged beneath each undercut 71, and each of these plates is provided between its ends with a semicylindrical notch 79. The notches 75 and 79 cooperate to form a bearing at each side of the plate 76 receiving a cylindrical pin Bil forming a rocking means for sup porting the plate 70 relative to the plates 73.

The plates 7 8;. obviously are supported for sliding movement on the shoulders 43 of the bed plate 11 and the entire assembly of the elements 70, 72, and 78 and 80 is guided for lineal movement by the portions of the plates 72 underlying and slidable against the bottom surfaces of the bed plate 11. It will be. noted that the upper surfaces of the bearing plates 78; slope downwardly in opposite directions from the notches 79 to provide space for the. rocking of the plate 70. The upper surfaces of the portions of'the plates 72 (Figures 3- and 4) lying beneath the bed plate 11 aije similarly sloped to accommodate the roclging movement of the plate 70. In any posid n Qf he nitlfi p 'situ nally of he e pl it will. pp e hat h fs ides 47 o uch ni fix to the plate. 70, may rock on the pins 80,, the slope of the upper surfaces of the plates 7,8 from the horizontal being greater than the sloping of the undercut surfaces, 74-, as clearly shown in Figures 3. and 4. Thus, it will be apparent that the. guide 47, cross head 52 and cutter bar 57 of the unit 66 are adapted to tilt from the vertical.

The lateral edges Of' the plate 70 extend downwardly below the undercuts 71 as at 84 (Figure 7). The inner edge portion 84 ofthe plate 7 Qis connectedto the upper end of a tension spring 85, the lower end of which is connected as at 86 to befixed with respect to the frame t will. evv appar nt herefore. that h plate 70 is normally biasedfto the position shown in Figure 3. Under conditions. to bed cribed, the plate 70 can be oppositely tilted, for example tolhe. position, shown in Figu e- 4.

Referring to Figures. 3; 941.5; it will be noted, that the cross head 33 is providedwith a, T, slot 88.. In this slot is slidable a guide 89, somewhatv elongated relative to the slot 88. This guide carries a pin 90. connecting it to the upper endofa bolt 91fixed to a cap 92 which in turn is fixed to the upper end. of the crosshead 52 of the unit 66. The slide 89 is movable freely in the T slot 88 under allconditions to permit the unit 66 to alter its inclination from the vertical. The pin preferably operates in a vertically elongated slot 93. A gap 93' is provided between, the upper; end of the bolt 91 and the guide-89 for apurppse to be described.

A cap,94, whichirnay, beidenticalfwiththe cap 92, is

carried by the. upper end ofthe cross head 52 of the unit 65. A bolt 96 iscennected atits lower end to the cap 94 andcarries at its upperL end ahead 97 slidahle in the T slot 83;;. A head;98. is ,carriedlby the bolt 96, m1. p stit es. artntameansfo m n 1 p tof. the present inyentioni fpr, adjustingithe. height of the associated, knife;- in relation; t its die.

Each of the plates 78 is provided toward the adjacent side, of. the apparatus.upstanding lug 100. engaged by a hemispherical member 101 carried by the inner end of a spring 102 the outer end of which backs up against an adjusting screw 103 threaded through a bracket 104 carried by the base 10. The springs 102 act on the plates 78 to move them toward the left in Figures 3 and 4, carrying with them the pins 80, the associated plate 70 and the elements carried thereby. When inserting a pack into the apparatus, the advancing edge of the pack is moved into engagement with rear stops 108 to limit the movement of the pack, and the left-hand edge of the pack as viewed in Figures 1, 2 and 3 is engaged with a side guide 109 fixed to the adjacent plate 44. In so placing the pack, the operator pushes against the righthand side thereof, thus lining up the left-hand side of the pack, as viewed in Figure 2, against the vertical inner surface of the guide 109. Under such conditions, the edge of the pack engaging the guide 109 will be the edge 110 (Figures 8 and 9), and such edge of the pack will be perfectly vertical.

A similar side guide 112 is fixed to the plate 70, and accordingly rocks therewith about the pins 80. This side guide is spaced from the adjacent edge of the pack as shown in Figure 2 when the parts are in their normal positions, thus facilitating the placing of the pack as described above. It will be apparent from Figure 2 that the base of the guide 112 overlies the adjacent plate 39. Such overlying portion of the base of the guide 112 is undercut to provide clearance with respect to the adjacent plate 39 to permit the free swinging of the unit 66.

A mechanism to be described releases the unit 66 for movement to the left in Figure 2 to bring the guide 112 into engagement with the adjacent edge of the pack. Such guide will engage solidly against the edge of the pack and will determine the tilting of the unit 66 from the vertical according to Whether the adjacent edge of the pack slopes upwardly and inwardly as at 113 (Figure 8) or downwardly and inwardly as at 114 (Figure 9), the inward movement of the unit 66 'being effected by the springs 102.

Referring to Figures 2 and 6, it will be noted that the plate 70 at the outside edge thereof is provided with ears 118 arcuately slotted as at 119. The ears 118 are mounted and secured in a milled-out slot 120 in the plate 70 (Figure 7).

A bar 121, outwardly of the adjacent plate 70, is mounted to slide in a bracket 122 fixed to the side frame 10. The inner end of the bar 121 carries a pin 123 extending through the slots 119. The bracket 122 is provided with an opening 124 vertically therethrough to support for vertical movement a slidable cam bar 125. This bar extends through a slot 126 formed in the bar 121. The bar 125 is provided with an angular cam surface 127 beneath which is a straight vertical surface 128 normally bearing against a roller 129 rotatably supported in the slot 126. The cam bar 125 is connected by suitable means 130, including a turnbuckle, with the cross head 33.

Substantially in accordance with the prior patent referred to, hold-down plungers 134 are provided for holding down the sheets of the pack to be round-cornered. These plungers are slidable in cylinders 135 carried by the cross head 33, and adjustable therealong by any suitable conventional means. The cylinders 135 are made of complementary, longitudinally separable parts forming no part of the present invention, the cover part being removed from the right-hand cylinder 135 in Figure 1 to show the internal spring 136 which biases the plungers 134 to their lower limit of movement shown.

Operation The parts normally occupy the positions shown in Figures 1, 2 and 3. When a pack is to be round-cornered, the operator will place the pack as shown in phantom lines in Figure 2, the advancing edge of the pack being pushed inwardly against the stops 108 and the left side of the pack being engaged with the side guide 109. The apparatus is now ready to be operated, and this operation is initiated by depressing the pedal 22 (Figure 1). This operation closes the switch 23 to energize the solenoid 19 and release the single revolution clutch 16 for engagement of the clutch elements. Thus the shaft 17 will be rotated through one complete revolution to perform the cutting operation, and at the end of such operation, the elements of the clutch 16 will be disengaged and the brake 24 will engage the shaft 17 to arrest movement thereof. The control mechanism just described forms per se no part of the present invention and need not be shown or described in detail.

Immediately upon initial revolution of the shaft 17, the disks 27 will start to rotate and pull downwardly on the connecting rods 29, thus moving the cross head 33 downwardly. Such movement of the cross head is imparted to the cam bar 125 to move the cam face 127 past the roller 129. Whereas this roller will have maintained the plate 70 of the unit 66 in the position shown in Figures 1, 2 and 3, the releasing of the bar 121 by operation of the cam permits the springs 102 to force the unit 66 toward the left as shown in Figures l-4, inclusive. Under such conditions, the side guide 112 acts as a jogger, engaging against the right-hand side of the pack 59, the left edge of the pack then lying in a vertical plane as at (Figures 8 and 9). If the pack has the edge thereof adjacent the side guide 112 sloped upwardly and inwardly as at 113 (Figure 8), the side guide 112 will remain approximately in the position shown in Figure 3. If such edge of the pack is vertical, the side guide 112 will engage flat against the edge of the pack and the unit 66 will have the parts thereof assume vertical positions. If the edge of thepack slopes upwardly and outwardly as in Figure 9, the side guide 112 will move to the position shown, for example, in Figure 4, the unit 66 being inclined upwardly and to the right from the vertical. In other words, regardless of the angularity of the right-hand edge of the pack referred to above, within the limits of inaccuracy generally encountered, the side guide 112 can accommodate itself to the angularity of the side of the pack. The upper end of the unit 66 is permitted to slide by engagement of the head 89 (Figure 5) in the slot 88.

Immediately after the releasing of the unit 66 for the movement described above, the hold-down plungers 134 will engage the top of the pack of sheets, after which the cutting operation will be performed. With the sheets held down by the plungers 134, the cutting edge 58 of the unit 65 will move vertically downwardly to cut the corner of the pack. The inserted edge of the pack and the lefthand edge thereof as viewed, for example, in Figure 2 will be perfectly vertical, and vertical movement of the cutting edge 58 referred to will accurately out such corner of the pack.

The cutting edge 58 of the unit 66 will move downwardly in the path of travel predetermined by solid engagement of the side guide 112 with the pack as described above. The cutting blade 58 will move vertically in the plane of the advancing edge of the pack, that is, the inner edge in Figure 2, which is vertical, but will move at any necessary angle relative to the right-hand edge of the pack in accordance. with the angularity of such edge of the pack. Therefore every sheet in the pack at the right-hand side thereof will be cut as accurately as at the left-hand side thereof.

The cutting operation will be performed by the time the cranks 28 reach their lower limits of movement, that is, with the shaft 17 having rotated through one-half a revolution. The cutting operation thus will be completed during downward movement of the cross head 33 and the parts connected thereto, whereupon the next half revolution of the shaft 17 will restore the cross head 33 to its normal upper position. Operation of the apparatus then will be arrested in the manner described above.

The slot 93 is provided to compensate for slight differences in the height of the pin 9?. incident to swinging movement of the unit 66. In this connection it will be noted that after a cutting operation has been performed, the vertically reciprocable parts of the cutting units are lifted by the pin 90. It is desired, however, to relieve this pin of the heavy thrust incident to the performance of the cutting operation. To this end, the height of the slot 93 above the pin s is greater than the height of the gap 93. is performed, therefore, the play in the gap 93' will be taken up to transmit a direct thrust from the slide 89 to the bolt 91 without placing any shearing stresses on the pin 90.

If the other two corners of the pack are to be similarly cornered, the operator will remove the pack, turn it in its own plane 180, and re-insert the pack in the apparatus as before. The depression of the treadle 22 will then initiate the next cutting operation, upon the completion of which all four corners of the pack will be accurately rounded. It will be apparent that if the first two corners are cut with the right-hand edge of the pack inclined to the vertical, the turning of the pack 180 will place the non-vertical edge of the pack against the side guide 169. However, inward. movement of the unit 66 will again jog the sheets into proper position against the guide 109. In reversing the pack, therefore, the previously vertical edge of the pack, if the pack is not accurately cut, will not be perfectly vertical and the unit 66 will operate to cut the corners of the pack accurately as in the case first described.

From the foregoing, it will be apparent that whereas the apparatus of the prior patent referred to is fully operative for cutting the corners of packs all edges of which are vertical, it is inaccurate in its cutting if the draw of the pack throws any side edge thereof out of parallelism with the opposite edge. The present apparatus operates automatically to compensate for inaccuracies in the shape of the pack. Accordingly, each operation may be quickly and easily carried out and the apparatus automatically compensatesfor inaccuracies in the shape of the pack. Thus, all of the corners cut by the present apparatus will be accurately out, each edge being accurately tangent to the curvature of the corners of the pack as cut.

Incidentally, it will be apparent that the unit 65 may be adjusted transversely of the apparatus to accommodate the mechanism to packs of varying widths. Such adjusting means forms no part of the present invention, and it will be obvious that the plate 44 of the unit 65 may be suitably clamped in any adjusted position longitudinally of the shoulders 43.

It will be apparent that in the operation of the present apparatus the unit 66 is adapted to swing back and forth through a vertical position to assume an inclined position in either direction. The spring 86 biases the unit 66 to one of its limits of movement from which it is easily movable merely upon inward lateral movement of the unit 66 to engage the guide 112 with the adjacent edge of the pack. The only operations in the apparatus which need be manually performed are the placing of the pack in position in the apparatus and the depression of the treadle 22. All of the other functions of the apparatus are fully automatic.

The present invention has been particularly described with reference to the rounding of the corners of packs of paper sheets, since this is the principal use to which the apparatus ordinarily is put. It will be apparent, however, that the machine is not limited in its use to the cutting of round corners, since obviously the knives and dies may be so formed as to square, bevel, or otherwise shape the corners of the sheets. Where the expression round cornering is used in the claims, therefore, it is When the cutting operation to he understood that this expression is intended to be used in a broader sense" than merely to describe a machine which forms round corners as distinguished from corners of other shapes.

It is to be understood that the form of the invention shown and described is to be taken as a preferred example of the same and that various changes in the shape, size, and arrangement of the parts may be made as do not depart from the spirit of the invention or the scope of the appended claims.

I claim:

1. A round-cornering machine comprising a horizontal support, a pair of spaced cutting units each comprising upstanding guide means and a round-cornering cutting element reciprocable in such guide means, guide elements carried by the respective cutting units and engageable with opposite edges of a pack of sheets arranged on said support, means for reciprocating said cutting elements, means for mounting one of said cutting units for movement toward and away from the other unit, the guide element associated with said one cutting unit being normally spaced from the adjacent edge of the pack of sheets, and means for supporting said one cutting unit for rocking movement on a horizontal axis whereby, when said one cutting unit is moved to engage its guide element with the adjacent edge of the pack of sheets, the guide means and cutting element of said one cutting unit will aline itself with respect to said adjacent edge of the pack of sheets.

2. A round-cornering machine comprising a horizontal support, a pair of spaced cutting units each comprising upstanding guide means and a round-cornering cutting element reciprocable in such guide means, guide elements carried by the respective cutting units and engageable with opposite edges of a pack of sheets arranged on said support, means for reciprocating said cutting elements, means for mounting one of said cutting units for movement toward and away from the other unit, the guide element associated with said one cutting unit being normally spaced from the adjacent edge of the pack of sheets, means for supporting said one unit for limited rocking movement in opposite directions from a vertical position, and means for biasing said one cutting unit for rocking movement to one of its limits of movement whereby, when said one cutting unit is moved to engage its guide element with the adjacent edge of the pack of sheets, the guide means and cutting element of said one unit will aline itself with respect to said adjacent edge of the pack of sheets.

3. A round-cornering machine comprising a horizontal support, a pair of spaced cutting units each comprising upstanding guide means and a round-cornering cutting element reciprocable in such guide means, guide elements carried by the respective cutting units and engageable with opposite edges of a pack of sheets arranged on said support, means for reciprocating said cutting elements, means for mounting one of said cutting units for movement toward and away from the other unit, the guide element associated with said one cutting unit being normally spaced from the adjacent edge of the pack of sheets, means for supporting said one cutting unit for rocking movement on a horizontal axis whereby, when said one cutting unit is moved to engage its guide element with the adjacent edge of the pack of sheets, the guide means and cutting element of said one cutting unit will aline itself with respect to said adjacent edge of the pack of sheets, means biasing said one cutting unit for movement toward said edge of the pack, and holding means normally operable for opposing said biasing means to hold the guide element associated with said one cutting unit spaced from said adjacent edge of the pack of sheets, said holding means being connected to said reciprocating means to be released when said cutting elements move toward the pack of sheets.

4. A round-cornering machine comprising a horizontalsupport, a pair of cutting units each comprising upstanding guide means, and a round-cornering cutting element mounted for reciprocation in such guide means, guide elements adjacent the respective cutting units engageable with opposite edges of a pack of sheets arranged on said support, an upper cross head, means slidably connected to said cross head for connecting it to the cutting element of one of said cutting units, means for supporting said one cutting unit for sliding movement on said support toward and away from the other unit, the cutting element of the other cutting unit being connected to said cross head, and means for supporting said one cutting unit for rocking movement on a horizontal axis whereby, when said one cutting unit is moved to engage its guide element with the adjacent edge of the pack of sheets, the guide means and cutting element of said one cutting unit will aline itself with respect to said adjacent edge of said pack of sheets.

5. A machine according to claim 4 wherein said means for supporting said one cutting unit for rocking movement comprises a plate carried by such unit, and pivot means connected between said plate and said means for supporting said one cutting unit for sliding movement on said support.

6. A machine according to claim 4 wherein said means for supporting said one cutting unit for rocking movement comprises a first plate, said means for supporting said one unit for sliding movement comprising a second plate slidably mounted on said support, said plates having adjacent faces provided with grooves receiving rocker pins.

7. A machine according to claim 4 wherein said means for supporting said one cutting unit for rocking movement comprises a first plate, said means for supporting said one unit for sliding movement comprising a second plate slidably mounted on said support, said plates having adjacent faces provided with registering semi-cylindrical grooves between the ends of such plates, rocker pins in said grooves, said plates having their adjacent faces in the region of said pins in close proximity to each other and relatively diverging transversely thereof to provide engageable stop surfaces to limit swinging movement of said first plate.

8. A round-cornering machine comprising a horizontal support, a first guide means fixed at its lower end to said support and projecting upwardly perpendicular thereto, a first round-cornering cutting element mounted for vertical reciprocation in said first guide means, a second guide means above said support spaced from and generally parallel to said first guide means, a second round-cornering cutting element slidable in said second guide means, means connecting said second guide means to said support for linear movement toward and away from said first guide means and for rocking movement on a horizontal axis perpendicular to said linear movement, a pair of guide elements adjacent and in fixed relation to the respective guide means and adapted to engage opposite edges of a pack of sheets arranged therebetween, the guide element adjacent said second guide means being fixed thereto and being normally spaced from the adjacent edge of the pack, movement of the guide element adjacent said second guide means into engagement with said adjacent edge of the pack jogging the pack and causing such guide element to lie flat against the edge of the pack to aline said second guide means and said second cutting element with respect to said adjacent edge of the pack, and common means for forcing said cutting elements downwardly to cut the corners of the pack.

9. A round-cornering machine comprising a horizontal support, a first guide means fixed at its lower end to said support and projecting upwardly perpendicular thereto, a first round-cornering cutting element mounted for vertical reciprocation in said first guide means, a second guide means above said support spaced from and generally parallel to said first guide means, a second round-cornering cutting element slidable'in said second guide means, means connecting said second guide means to said support for linear movement toward and away from said first guide means and for rocking movement on a horizontal axis perpendicular to said linear movement, a pair of guide elements adjacent and in fixed relation to the respective guide means and adapted to engage opposite edges of a pack of sheet arranged therebetween, the guide element adjacent said second guide means being fixed thereto and being normally spaced from the adjacent edge of the pack, movement of the guide element adjacent said second guide means into engagement with said adjacent edge of the pack jogging the pack and causing such guide element to lie flat against the edge of the pack to aline said second guide means and said second cutting element with respect to said adjacent edge of the pack, an upper cross head connected to said first cutting element, and means connecting said cross head to said second cutting element, such means being longitudinally slidable relative to said cross head to accommodate said rocking and linear movements of said second guide means and said second cutting element.

10. A machine according to claim 9 provided with means for limiting rocking movement of said second guide means to each side of the vertical, and means biasing said second guide means to one of its limits of movement.

11. A machine according to claim 9 provided with means biasing said second guide means for linear movement toward the pack of sheets, and holding means normally holding the second-mentioned guide element away from said adjacent end of the pack of sheets, said holding means being connected to said cross head to be released upon downward movement of the latter.

12. A machine according to claim 9 provided with means for limiting rocking movement of said second guide means to each side of the vertical, means biasing said second guide means to one of its limits of movement, means biasing said second guide means and the adjacent guide element toward said adjacent edge of the pack, and holding means normally holding the last-mentioned guide element spaced from said adjacent edge of the pack, said holding means being connected to said cross head to be released upon downward movement thereof from a normal upper position.

13. A round-cornering machine comprising a horizontal support, a first guide means fixed at its lower end to said support and projecting upwardly perpendicular thereto, a first round-cornering cutting element mounted for vertical reciprocation in said first guide means, a second guide means above said support spaced from and generally parallel to said first guide means, a second roundcornering cutting element reciprocable in said second guide means, a first plate slidably mounted in said support for movement toward and away from said first guide means, a second plate above said first plate and to which said second guide means is fixed, pivot means connecting said plates for rocking movement on a horizontal axis perpendicular to the direction of sliding movement of said first plate, a pair of guide elements adjacent and in fixed relation to the respective guide means and adapted to engage opposite edges of a pack of sheets arranged there between, the guide element adjacent said second guide means being normally spaced trom the adjacent edge of the pack, movement of the guide element adjacent said second guide means into engagement with said adjacent edge of the pack jogging the pack and rocking said second guide means on said pivot means and causing the lastmentioned guide element to lie flat against the edge of the pack to aline said second guide means and said second cutting element with respect to said adjacent edge of the pack, and common means for forcing said cutting elements downwardly to cut the corners of the pack.

14. A machine according to claim 13 wherein said pivot means comprises pivot pins, the adjacent faces of said plates having semi-cylindrical registering recesses receiving said pivot pins.

15. A machine according to claim 13 wherein said pivot means comprises pivot pins, the adjacent faces of said plates having semi-cylindrical registering recesses receiving said pivot pins, said adjacent faces of said plates relatively diverging laterallyv away from said pivot pins to provide stop faces limiting rocking movement of said second guide means about the axis of said pivot pins, and means biasing said second plate to one of said limits of movement.

16. A machine according to claim 13 wherein said pivot means comprises pivot pins, the adjacent faces of said plates having semi-cylindrical registering recesses receiving said pivot pins, said adjacent faces of said plates relatively diverging laterally away from said pivot pins to provide stop faces limiting rocking movement of said second guide means about the axis of said pivot pins,

meansbiasing said second plate to one of said limits of movement, and means normally holding said first plate in a position with the guide element for said second guide means spaced from said adjacent edge of the pack, such means being connected to said common means to be released upon downward movement of said cuttingelements, and vmeans biasing said first plate for movement toward said adjacent edge of the pack.

References Cited in the file of this patent UNITED STATES PATENTS 1,346,589 Cameron July 13, 1920 1,957,711 Heyman May 8, 1934 2,589,033 Baumgartner Mar. 11, 1952 2,620,874 Chase Dec. 9, 1952 2,656,888 Cruzan Oct. 27, 1953 

